The Todd Engineering PS260 is an RV automatic transfer switch that routes power among shore (land line), generator, and inverter sources by closing a set of relays. Common failure points include worn or stuck relay contacts, failed selector contacts, or a malfunctioning control board that fails to detect the inverter input; these issues often manifest as the unit switching correctly between shore and generator but not engaging the inverter path. First‑check steps: verify the inverter’s output voltage and polarity with a multimeter while the PS260 is commanded to select it; inspect relay contacts for corrosion or pitting and test the control logic with an oscilloscope or diagnostic tool; finally, review any error codes displayed on the unit’s panel or in its log.[oss-gpt-20b]